I panicked about this too. Get a thin flat screwdriver, wedge the old splitter out and slip the new one in.
2 Middle clips were not fun, just bang and bang and bang and bang. Eventually gets the message.
 
I paid just short of £20 from my SEAT dealer. Not sure if youre going to get it for much less online.

Not sure of part number. Simply phone dealer and give them your chassis number. Can order the exact part for you. I believe there are 3 different splitters for the LCR, hence the VIN number to get the right one.